chapter 1 VWO 3
materials and substances
,● 1.1 Materials
● boiling point = The temperature at which a substance boils.
● Composite = A mix of materials used to achieve better material properties
● Density = The mass of a material or substance per unit volume
● Electrical conductivity = How well substances and materials conduct electricity
● Hydrophilic = Absorbing water or soluble in water
● Hydrophobic = Repelling water or insoluble in water
● Material properties = The characteristics of a material such as its hardness,
density and electrical conductivity
● melting point = The temperature at which a substance melts
● Natural materials = Materials of natural origin such as bone, wood and stone
● Phase = The state of matter for a substance: solid, liquid or gaseous
● Plastic = A synthetic material that is (usually) made from petroleum
● Properties of a substance = Characteristics of a pure substance such as its
density, boiling and melting point
● Raw materials = Substances that are needed for making synthetic materials
● Renewable raw materials = a raw material that does not get exhausted,
usually biological origin
● Solubility = How well substances dissolve in a liquid (usually water)
● Synthetic materials = Materials that have to be made from raw materials using
chemical processes
● Thermal conductivity = How well substances and materials conduct heat
- Materials can be classified into natural and synthetic materials.
Natural materials are things like stone, wood, bone and coal. Raw materials are
substances that you need to make materials that can not be found in nature. The
materials that are made from raw materials are called synthetic materials. Brick, iron
and glass are examples of synthetic materials. But the term synthetic materials
usually refers to plastic nowadays.
- Plastics are largely synthesized from petroleum at the momentast
Plastics are almost everywhere today. They are mostly made from petroleum as their
raw materials, but by making plastic from petroleum a large amount of complex
processes are used. But because this causes pollution and petroleum is scarce,
biological raw materials are used more often. Biological raw materials are renewable
raw materials. We do not run out of them because more can be grown.
- The material that you select for an application depends on the properties of the
material
, Which material you choose for something depends on the properties of that material,
material properties, or in cases where the material is a pure substance we call them
properties of a substance or substance properties. You can determine the properties
of any pure substance. They are specific to the substance and can be used to
identify it.
Material examples explanation
properties
Density Iron has a high density but Every material has its own specific
aluminum’s density is low. mass per unit. You can use the
The density of alcohol is 0.80 kg/l density to calculate the volume of a
given mass of that material and
vice versa.
elasticity Rubber is elastic, but a pebble How elastic a material or substance
doesn’t bounce is.
Electrical Metals like copper and gold How well a substance lets
conductivity conduct current well, but plastics electricity pass through
do not
hardness Concrete is hard but chalk is soft How hard something is.
hydrophilic/ Cotton absorbs liquid but plastics A material that is bad at absorbing
hydrophobic are water-repellent water or letting water through is
hydrophilic. A material that absorbs
water well is hydrophobic.
boiling/ The melting point of carbon is When a substance starts to melt
melting 3550 ˚C but the melting point of (solid to liquid phase) or when it
point hydrogen is -259 ˚C starts to boil ( liquid to gaseous
phase) .
solubility Sugar dissolves well in water but How much and how easily a
oil doesn’t substance dissolves in liquid
(water).
Heat Metals like copper and gold How well the substance lets heat
conduction conduct heat well, but plastic pass through. also called thermal
doesn’t conductivity.
- In a composite, materials are mixed together to achieve better materials properties
Sometimes there is no suitable material available for a certain application. There are
two things that can be done: try to develop a new material, or combine the properties
of two known materials. This is called a composite